Magnetic field sensor device configured to sense with high precision and low jitter

ABSTRACT

Magnetic field sensor devices and associated methods are disclosed. Magnetic field sensor devices may comprise a first magnetic field sensor having a first bridge part spatially separated from a second bridge part. In some implementations, a second magnetic field sensor may be arranged between the first bridge part and the second bridge part. With this arrangement, measurements read by the magnetic field sensor device have high precision and low jitter.

TECHNICAL FIELD

The present application relates to magnetic field sensor devices,methods of operating magnetic field sensor devices and methods formanufacturing magnetic field sensor devices.

BACKGROUND

Magnetic field sensors are used in many applications. For example, forspeed or movement detection, magnets may for example be provided on aso-called pole wheel, a magnetic encoder or other magnetic element, thusgenerating a modulated magnetic field when the pole wheel rotates. Themodulation of the field may then be detected by a magnetic field sensor.The magnetic field detected thereby and its modulation are thenindicative for example of a rotational speed of the pole wheel. Insteadof a pole wheel, e.g. also a linear magnetic element generating amodulated magnetic field when moving may be used. For such a speeddetection, in many applications a high accuracy and low jitter arerequired. To achieve this, in some applications sensors based on giantmagnetoresistance (GMR) or tunnel magnetoresistance (TMR) have beenincreasingly used, although other types of magnetic field sensors likeanisotropic magnetoresistance (AMR)-based sensors or Hall sensingelements may also be used. Besides detecting the speed, in someapplications, it is desirable to also obtain some measure of theabsolute magnetic field.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a magnetic field sensor deviceaccording to an embodiment.

FIG. 2 is a schematic circuit diagram of a magnetic field sensor deviceaccording to an embodiment.

FIG. 3 is layout example of a magnetic field sensor device according toan embodiment.

FIG. 4 is a layout example of a part of a magnetic field sensor deviceaccording to an embodiment.

FIGS. 5A and 5B are implementation examples of resistors usable in someembodiments.

FIG. 6 is an application example of some embodiments.

FIGS. 7A and 7B are diagrams illustrating the sensing of magnetic fieldsaccording to embodiments.

FIG. 8 is a diagram illustrating a response of a magnetic field sensorusable in some embodiments.

FIG. 9 is a flow chart illustrating a method of operating a magneticfield sensor device according to an embodiment.

FIG. 10 is a flow chart illustrating a method of manufacturing amagnetic field sensor device according to an embodiment.

DETAILED DESCRIPTION

In the following, various embodiments will be described in detail withreference to the attached drawings. It is to be noted that theseembodiments serve illustrative purposes only and are not to be construedas limiting. For example, while embodiments are described comprising aplurality of different details, features or elements, in otherembodiments some of these details, features or elements may be omitted,may be implemented in a different manner than shown, and/or may bereplaced by alternative details, features or elements. Additionally oralternatively, in other embodiments, additional details, features orelements not explicitly described herein may be present. Connections orcouplings, for example electrical connections or couplings shown in thedrawings or described herein may be direct connections or indirectconnections, indirect connections being connections with one or moreadditional intervening elements, as long as the general function of therespective coupling or connection, for example to transmit a certainkind of information in form of a signal, is maintained. Furthermore,connections or couplings may be implemented as wire-based connections orwireless connections unless specifically noted otherwise.

In some embodiments, magnetic field sensor devices are provided. In someembodiments, a magnetic field sensor device may comprise a firstmagnetic field sensor and a second magnetic field sensor. The firstmagnetic field sensor may comprise a bridge circuit with spatiallyseparated bridge branches, and the second magnetic field sensor may bearranged e.g. between the spatially separated bridge branches of thefirst magnetic field sensor. In some applications, the first magneticfield sensor may be used to sense a modulation of a magnetic fieldcorresponding to a speed, whereas the second magnetic field sensor maybe used to sense a measure of a magnetic field strength, for examplecorresponding to a proximity of a magnet to the magnetic field sensordevice, e.g. an air gap between the magnet and the magnetic field sensordevice. The second magnetic field sensor in some embodiments may alsocomprise a bridge circuit, with bridge branches of a second magneticfield sensor device being significantly closer to each other, forexample smaller by about one order of magnitude or more, than at leastsome of the bridge branches of the first magnetic field sensor.

Turning now to the figures, in FIG. 1 a magnetic field sensor deviceaccording to an embodiment is shown. The embodiment of FIG. 1 comprisesa first magnetic field sensor which comprises a bridge circuit. Thebridge circuit comprises a first bridge part 10 and a second bridge part12 which are spatially separate from each other. A distance between thefirst bridge part 10 and the second bridge part 12 may be more than 100μm in one embodiment, for example of the order of some millimeters, butmay also have other values. In some embodiments, the first magneticfield sensor comprising the first bridge part and the second bridge partmay serve to detect a movement for example of a pole wheel or anotherentity which moves and generates a modulation of a magnetic field whilemoving. A modulation as used herein generally may refer to a variationover time and may be periodic or non-periodic.

In such an application, a distance between first bridge part 10 andsecond bridge part 12 may for example correspond to a pitch of the polewheel or other moving magnetic device, for example a distance betweenindividual magnets on the pole wheel or other magnetic device. Firstbridge part 10 and second bridge part 12 may be implemented usingresistors based on materials and/or structures exhibiting, for example,a giant magnetoresistance (GMR) or a tunnel magnetoresistance (TMR),such that the presence of a magnetic field causes a change ofresistance, which in turn leads to a change of one or more outputvoltages of the bridge circuit. Such output voltages may be received bya control circuit 13 to, for example, determine a speed of a magneticdevice moving past the first magnetic sensor, as explained above. Inother embodiments, control 13 may evaluate signals received from firstand second bridge parts 10, 12 in any other way to obtain desiredinformation based on a sensed magnetic field. In other embodiments,other magnetoresistive effects, generically referred to as XMR, may beused, for example anisotropic magnetoresistance (AMR) or colossalmagnetoresistance (CMR).

Furthermore, the embodiment of FIG. 1 comprises a second magnetic fieldsensor 11. In embodiments, second magnetic field sensor 11 is locatedspatially between first bridge part 10 and second bridge part 12,although it need not be located in the middle between first bridge part10 and second bridge part 12, but may also be located closer to eitherfirst bridge part 10 or second bridge part 12 or may be locatedelsewhere.

Second magnetic field sensor 11 in embodiments may be used to obtain ameasure of a magnetic field strength at or near the magnetic fieldsensor device. Such a magnetic field strength may, for example, beindicative of a proximity of magnets, for example magnets of a polewheel or other magnetic device, to the magnetic field sensor device. Thesignal from second magnetic field sensor 11 may be evaluated by controlcircuit 13 in some embodiments. In some embodiments, second magneticfield sensor 11 may also comprise a bridge circuit, bridge branches ofthe bridge circuit of the second magnetic field sensor being closertogether than bridge branches of the first magnetic field sensor, forexample within a distance of 10 to 50 μm, but not limited thereto. Inother embodiments, the bridge branches of the first and/or secondmagnetic field sensors may be interlaced and/or nested with each other.

In some embodiments, second magnetic field sensor 11 may also compriseresistors made of materials and/or having structures leading to GMR orTMR effects, although other effects may as well be used for detectingmagnetic fields. For example, in other embodiments, othermagnetoresistive effects, generically referred to as XMR, may be used,for example anisotropic magnetoresistance (AMR) or colossalmagnetoresistance (CMR).

In some embodiments, the first magnetic field sensor comprising firstbridge part 10 and second bridge part 12 and the second magnetic fieldsensor 11, may be implemented for example on a semiconductor or othersubstrate using the same processing techniques for both magnetic fieldsensors. For example, this may be done in cases where the secondmagnetic field sensor 11 also uses a bridge circuit with resistors madeof the same or similar materials than resistors of first bridge part 10and second bridge part 12. In some embodiments, this may facilitatemanufacturing the magnetic field sensor devices, for examplesimultaneous manufacturing of the first and second magnetic fieldsensors without additional processing steps.

It should be noted that in some applications, second magnetic fieldsensor 12 may also be implemented outside the first and second bridgebranches 10, 11 of the first magnetic field sensor.

In some embodiments, a magnetic field acting on the first magnetic fieldsensor of the device of FIG. 1 also acts on the second magnetic fieldsensor or vice versa, even if the signals output may differ due to, forexample, different geometries of the first and second magnetic fieldsensors. In some embodiments, this may be used to employ safetymechanisms. For example, when the first magnetic field sensor senses amodulated magnetic field without the second magnetic field sensorsensing anything, this may indicate a fault of the second magnetic fieldsensor (or even a fault of the first magnetic field sensor). Conversely,when the second magnetic field sensor senses a magnetic field, withoutthe first magnetic field sensor sensing anything, this may be indicativeof a fault of the first magnetic field sensor. Such circumstances whichmay indicate a fault may be detected by control circuit 13, and in casesuch a circumstance is detected, for example a signal indicating apossible fault may be output.

In FIG. 2, a magnetic field sensor device according to a furtherembodiment is shown. The magnetic field sensor device of FIG. 2comprises a first magnetic sensor formed by a differential bridgecircuit, comprising resistors R1 to R4, as shown. Resistors R1 to R4 maybe made of or comprise materials and/or structures exhibiting a giantmagnetoresistance (GMR) or a tunnel magnetoresistance (TMR), although inother embodiments other techniques may also be used. In someembodiments, resistors R1-R4 may have a same design, e.g. have a sametransfer function describing their resistance depending on an appliedmagnetic field. Voltages obtainable from the differential bridge arelabeled Vbridge1 and Vbridge2 in FIG. 2, and may, for example, beevaluated by a control circuit like control circuit 13 of FIG. 1 toobtain, for example, information regarding a speed of a magnetic devicemoving adjacent to the magnetic field sensor device. Such a magneticdevice may, for example, comprise a pole wheel or a linear magneticdevice comprising magnets.

Resistors R1 and R4 in FIG. 2 are an example for a first bridge partlike first bridge part 10 of FIG. 1, and resistors R2 and R3 are anexample for a second bridge part like second bridge part 12 in FIG. 1,the first bridge part being spatially separate from the second bridgepart. In some embodiments, with an arrangement as shown in FIG. 2,detection of a movement with high precision and/or low jitter may bepossible.

Furthermore, the embodiment of FIG. 2 comprises a second magnetic fieldsensor, which is implemented in the example embodiment of FIG. 2 as aWheatstone bridge comprising resistors R5, R6, R7 and R8 which arecoupled as shown in FIG. 2 between a supply voltage V₀ and ground. Inother embodiments, other reference potentials may be used. Betweenresistors R5 and R7, a first voltage V1 may be tapped, and betweenresistors R6 and R8, a second voltage V2 may be tapped. Based on thefirst and second voltages V1 and V2, for example, based on a differencebetween V1 and V2, a measure for a magnetic field strength may beobtained. In some embodiments, R5 and R8 may be of a first resistortype, for example, a first size, and R6 and R7 may be of a secondresistor type, for example, of a second size. For example, the firstresistor type (say R6 and R7) may have a sensitivity range needed forthe detection of a magnetic field range present in a specificapplication (for example a range of up to 3 milliteslas (mT). Obviouslyother magnetic field ranges may be used, depending on the application.The second resistor type, for example R5 and R8, may have a highersensitivity range than the first resistor type, for example asensitivity range as large as possible given design constraints and areaconstraints. For example, a width of resistors R6 and R7 may beapproximately half a width of resistors R5 and R8 in some embodiments.For example, a width of resistors R6 and R7 may be approximately 0.8 μmand a width of R5 and R8 may be approximately 1.5 μm in some chipdesigns, although these values may vary depending e.g. on an applicationand/or depending on technologies used. Generally, in embodiments adesign of at least one of the resistors R5-R8 may differ from a designof at least one other of the resistors R5-R8, leading to differenttransfer functions.

In some embodiments such a bridge configuration may allow thecompensation of temperature offsets. The bridge formed by resistors R5to R8 may also be referred to as a spatially concentrated bridge, as thebridge branches are close together, in contrast to the bridge branchesformed by R1 to R4. For example, a distance between the bridge branchesformed by resistors R5 to R8 may be about one order of magnitude smallerthan a distance between the bridge branches of the bridge formed by R1to R4.

In FIG. 3, a schematic circuit layout showing a possible implementationof the circuit illustrated in FIG. 2 is shown. The circuit layout ofFIG. 3 serves only as an example and to illustrate implementationpossibilities further and is not be construed as limiting. In theexample of FIG. 3, a first bridge part is labeled 30 and may, forexample, comprise resistors R1 and R4 of FIG. 2, a second bridge part islabeled 31 and may, for example, comprise resistors R2 and R3 of FIG. 2,and a second magnetic field sensor which may, for example, compriseresistors R5 to R8 of FIG. 2 is labeled 32 and is located between firstbridge part 30 and second bridge part 31. Additionally, FIG. 3 showscontact pads for electrically contacting first bridge part 30, secondbridge part 31 and second magnetic field sensor 32 as well asinterconnections. In some embodiments the contact pads may be replacedby interconnections to underlying control circuitry. As can be seen, inthe example implementation of FIG. 3, second magnetic field sensor 32 isnot in the middle between first bridge part 30 and second bridge part31, although in other implementations it may be located in the middle.Optionally, in a box labeled 33, further devices or elements may beprovided, for example further resistances or a bridge circuit sensitiveto a magnetic field or any other devices.

In some embodiments, second magnetic field sensor 32 and first andsecond bridge parts 30, 31 (e.g. all resistors R1-R8 in FIG. 2) may beformed by using a same process, e.g. using the same materials, whichfacilitates manufacturing the device of FIG. 3. In other embodimentssome of the resistors of the second magnetic field sensor may be formedusing identical layout but different materials or material thicknessesto create differences in transfer functions between different resistorsof the second magnetic field sensor.

In FIG. 4, an implementation example of a bridge circuit like the bridgecircuit formed by resistors R5 to R8 of FIG. 2 is shown in more detail.In the circuit layout example of FIG. 4, two “larger” resistors 40 and43, for example, resistors R5 and R8, and two resistors with reducedwidth 41 and 42, for example, resistors R6 and R7, are illustrated.Furthermore, the example circuit layout of FIG. 4 comprisesinterconnects and a plurality of contact pads 44, for example, forconnecting with supply voltages (like V₀ or ground of FIG. 2) and fortapping output voltages (like V1 and V2 of FIG. 2). By the showndifferent dimensioning of resistors 40, 43 on the one hand and 41, 42 onthe other hand, different sensitivities as explained above may beobtained. However, it is to be noted that this serves only as a simpleexample, and different sensitivities may also be obtained by othermeans, for example by choosing different materials, a different materialthickness or different number of layers etc. In some embodiments, bydesigning R5 and R8 larger than R6 and R7, also a temperature dependencyof R5 and R8 may be larger than a temperature dependency of R6 and R7,in case temperature dependent materials are used for implementation.However, in the bridge circuit design of the embodiment shown, thistemperature dependency is compensated by the bridge circuit used.

In FIGS. 5A and 5B, layout examples for the resistors 40 to 43 of FIG. 4are schematically shown. Such layouts may also be used for otherembodiments than the one shown in FIG. 4. FIG. 5A for example shows animplementation example of resistors 40 and 43 of FIG. 4 and FIG. 5Bshows an implementation example of resistors 41 and 42 of FIG. 4. Theimplementation of example of FIG. 5B is essentially a smaller version ofthe implementation example of FIG. 5A. In both cases, the resistor maybe formed by a plurality of elliptical elements coupled in series andmade of an appropriate material, for example a GMR or TMR material, ormaterial stacks, as briefly explained below. In the example case of FIG.5A, a size of the elliptical elements may, for example, be of the orderof 2×12 μm, and in the example case of FIG. 5B a size of the ellipticalelements may, for example, be of the order of 1.3×7.8 μm, although othersizes may also be used. This difference in sizes in embodiments may leadto a higher sensitivity of a resistor implemented as shown in FIG. 5A tomagnetic fields compared to a resistor implemented as shown in FIG. 5B.It should be noted that the number, size and arrangement of ellipticalelements is not limiting, and other numbers and arrangements may also beused. Furthermore, instead of elliptical elements also elements havinganother shape, for example rectangular or half moon shaped elements, maybe used. In yet other examples, other structures may be used toimplement magnetoresistive resistors.

Generally, the magnetoresistive resistors may be implemented as aconventional layer structure in some embodiments, for example comprisinga seed layer, a reference system layer, a non-magnetic spacer layer, afree layer comprising a magnetically active material and a cap. Theorder of reference system layer and free layer may be exchanged. Thefree layer may comprise ferromagnetic materials like Co, Fe, Ni, alloysthereof, or alloys of these materials with other materials like CoFeB.Also multilayers like CoFe/NiFe bilayers, or coupled layers likeCoFe/Ru/CoFe may be used as magnetically active materials within thefree layer.

For the reference system layer the same magnetically active material(s)as for the free layer may be used, or other materials, for examplemagnetically active materials like antiferromagnetic materials, e.g.PtMn, IrMn, NiMn, CrPtMn or others. The non-magnetic spacer may comprisemetals like Cu, Ag or Cr for GMR systems or non-conducting materialsserving as a tunneling barrier like MgO, HfO, AlN or aluminum oxides.The seed layer may serve to improve crystal properties of the layerstructure, and the cap layer protects the other layers. In otherembodiments, other structures may be used.

Resistors R1 to R4 of the embodiment of FIG. 2 or generally bridgebranches of a bridge circuit forming a first magnetic field sensor maybe implemented in a similar manner as shown in FIGS. 5A and 5B, but insome embodiments may, for example, have different shapes and/or sizesthan shown in FIGS. 5A and 5B, although other implementations may alsobe used. In case of similar implementations for the first and secondmagnetic field sensors, in some embodiments, this may facilitate asimultaneous manufacturing of first and second magnetic field sensorsusing, for example, same processes in production.

As already mentioned above, providing two magnetic field sensors may behelpful in safety critical applications as they provide redundancy. Whenthe second magnetic field sensor is formed using a bridge circuit asillustrated in FIG. 2 (R5-R8) or FIG. 4, the second magnetic fieldsensor may also be used to measure a speed (e.g. of a pole wheel orlinear element as will be explained below with reference to FIG. 6). Asa trade-off the accuracy may in some embodiments be lower that a speedmeasurement using the first magnetic field sensor (e.g. resistorsR1-R4). Even with lower accuracy however, such an additional speedmeasurement may provide redundancy or even diversity for the actualspeed. The speed information obtained with both magnetic field sensorsmay be used in order to provide a higher level of functional safetyand/or a plausibility check of a speed measured by the first magneticfield sensor.

On the other hand, as explained above, the second magnetic field sensormay be used to measure a magnetic field, e.g. to determine a proximityof a magnet to the magnetic field sensor device. In some embodimentsadditionally or alternatively a measuring of a static magnetic fieldstrength, e.g. of a constant bias field, is made possible by the secondmagnetic field sensor, which may be implemented as a bridge circuit witha comparatively small distance between its bridge branches as explainedabove. In such an embodiment, therefore the second magnetic field sensormay serve both to measure a magnetic field strength and to measure atleast a rough estimate of a speed to provide redundancy and/or aplausibility check.

In contrast thereto consider a device with e.g. two redundantdifferential bridges having bridge branches spaced apart from each othersimilar to the first magnetic field sensor described above. While speedcould be measured with both bridges in a redundant way, measuring of anabsolute field strength would be difficult, if not impossible with sucha device.

FIG. 6 shows a possible application environment of magnetic field sensordevices of some embodiments, e.g., as discussed above. In theapplication example of FIG. 6, a magnetic field sensor device 63, whichmay be implemented, for example, as discussed above with respect toFIGS. 1 to 5, is placed adjacent to a pole wheel 61. Pole wheel 61 ismounted to an axle 60. When axle 60 rotates, pole wheel 61 also rotates.Pole wheel 61 has a plurality of magnets 62 arranged circumferentiallyat its periphery. The arrangement and number of magnets shown in FIG. 6serves only as an example, and other arrangements or numbers of magnetsmay also be employed. Magnets 62 may be permanent magnets orelectromagnets, to give some examples. When axle 60 and therefore polewheel 61 rotates, the movement of magnets 62 causes a modulated magneticfield acting on magnetic field sensor device 63. The speed of modulationof the magnetic field in such an example is indicative of the speed ofrotation.

The application of FIG. 6 serves merely as an example, and magneticfield sensor devices as disclosed herein may also be used for otherapplications. For example, in a different example instead of a polewheel a linear magnetic element, for example, with a plurality ofmagnets arranged along its length, may be moving adjacent to magneticfield sensor device 63, thus also causing a modulated magnetic field.Such a linear magnetic element may, for example, be used to monitorlinear actuators, hydraulic cylinders or other devices involving alinear movement. In applications as discussed above, the first magneticfield sensor discussed above may be used to measure a speed or may beused to measure the angular or linear position of a magnetic encoder. Insuch an embodiment, bridge branches of the first magnetic field sensormay have a spacing corresponding to about half the pitch of magnets 62on pole wheel 61. When pole wheel 61 rotates, both bridge branches areexposed to a modulated magnetic field, with a phase difference betweenthe bridge branches. For example, in case the device of FIG. 3 is usedas magnetic field sensor device 63, magnets 62 pass resistors R1, R4 ata different time compared to resistors R2, R3, leading to a phasedifference, which is indicative of the speed. Furthermore, the secondmagnetic field sensor may be used to measure a proximity of the magnetsto the magnetic field sensor, e.g. an air gap, for example to ensurethat a distance or spacing is correct. In this way, a correctpositioning of the sensor device relative to the pole wheel may bemonitored, e.g. according to the so called AK protocol used in someautomotive applications, thus providing a safety function. Furthermore,as explained above, the presence of a second magnetic field sensor mayadd some redundancy which may lead to the detection of failures of oneof the magnetic field sensors, which may be desired, e.g., forsafety-critical applications.

In other embodiments, magnetic field sensor devices as illustrated abovemay be used, for example, for current sensing. A changing current leadsto a changing magnetic field, which may for example be detected by thefirst magnetic field sensors discussed above, for example with a bridgecircuit having spatially separate bridge branches. The second magneticfield sensor may then for example be used to detect external homogenousfields or a misalignment of the magnetic field sensor device, forexample of a chip on which the magnetic field sensor device isimplemented. In such embodiments, the second magnetic field sensor maybe placed for example in the middle between the spatially separatedbridge branches of the first magnetic field sensor.

Next, to illustrate embodiments further, with reference to FIGS. 7A, 7Band 8, example signals output by the first and second magnetic fieldsensors of some embodiments will be illustrated. These example signalsserve only for further illustration, and depending on implementation ofthe magnetic field sensors and external magnetic fields applied, thesesignals may look different.

In FIGS. 7A and 7B, example signals obtained from a first magnetic fieldsensor, e.g., as mentioned above, in the example of FIGS. 7A and 7B amagnetic field sensor comprising spatially separated bridge branches,are shown for different magnetic fields. FIG. 7A illustrates an examplecase where a distance between the spatially separate bridge branches isaligned to a pitch for example of a pole wheel. FIG. 7B illustrates acase with misalignment. As can be seen, the signals, including a peaksignal strength, differ from each other. In such embodiments, it istherefore difficult to measure for example a proximity of the magnets ofthe pole wheel to the magnetic field sensor device based on the magneticfield measured, as the measured values depend on an alignment.

In FIG. 8, a curve 80 shows an example response of a spatiallyconcentrated bridge serving as second magnetic field sensor, as, forexample, illustrated in FIG. 2 or FIG. 4. The signal generated inresponse to an external field in a certain region around zero is linearand exhibits a low hysteresis in some embodiments. This may, forexample, be used to measure a field strength, which in embodiments may,for example, serve as a measure for a proximity of the magnet to themagnetic field sensor device. In some embodiments, for example, magneticfields with peak strength up to about 2500 A/m may be measured, althoughthe second magnetic field sensor may also be designed for other valuesdepending on the implementation and/or desired application.

Next, with reference to FIGS. 9 and 10 some methods according to someembodiments will be discussed. While the methods will be described as aseries of acts or events, the order in which such acts or events aredescribed is not to be construed as limiting. Other orders are equallypossible, and acts or events described may also be performedconcurrently with each other. For example, several magnetic fieldmeasurements using different sensors may be performed concurrently,and/or the formation of different magnetic field sensors for example ona chip may be performed concurrently using some processes.

In FIG. 9, a method for operating a magnetic field sensor device, forexample, a magnetic field sensor device as discussed with respect toFIGS. 1 to 8 above, is illustrated. At 90, a magnetic field modulation,for example, indicative of a speed, is measured using a spatiallyseparated bridge, i.e., a bridge circuit with spatially separate bridgebranches. For example, for measuring the magnetic field modulation, thefirst magnetic field sensor as discussed above may be used. At 91, amagnetic field strength is measured with a sensor within the spatiallyseparated bridge used at 90, for example, a second magnetic field sensoras explained above. This may be used in some embodiments to measure aproximity of a magnet. Optionally, at 92 a fault detection is performed,for example, when only at 90 or only at 91 a magnetic field is measured.

In FIG. 10, a method for manufacturing a magnetic field sensor device,for example, for manufacturing any of the magnetic field sensor devicesdiscussed with reference to FIGS. 1 to 8 above, is shown. At 100, afirst magnetic field sensor with spatially separated bridge branches isprovided, for example, on a semiconductor substrate. At 101, the methodof FIG. 9 comprises providing a second magnetic field sensor, forexample, a bridge circuit having bridge branches adjacent to each other,between the spatially separated bridge branches of the first magneticfield sensor. Providing the first and second magnetic field sensors maycomprise providing resistors made of materials and/or structuresexhibiting a giant magnetoresistance (GMR) effect or a tunnelmagnetoresistance (TMR) effect. In some embodiments, the acts describedwith respect to 100 and 101 may be performed simultaneously, for exampleusing at least one common processing phase and/or using the sameprocesses for providing the first and second magnetic field sensors. Forexample, the first and second magnetic field sensors may each have GMRor TMR elements having a layer structure as explained above. The atleast one common processing phase may then e.g. comprise one or morematerial deposition phases to deposit materials like the ones mentionedabove for forming the layer structures, for example magnetically activematerials, one or more structuring phases, metallization phases and/orother phases needed to form the first and second magnetic field sensors.In some embodiments, only such common processing phases without separateprocessing may be used, although in other embodiments some part of theprocessing may be performed separately for the first and second magneticfield sensor.

It is to be emphasized again, that the above described embodiments serveonly as examples and are not to be construed as limiting the scope ofthe present application, as the techniques disclosed herein may also beimplemented in other ways than shown, as apparent to persons skilled inthe art.

What is claimed is:
 1. A magnetic field sensor device, comprising: afirst magnetic field sensor, the first magnetic field sensor comprisinga first bridge circuit, a first bridge part of the first bridge circuitbeing spatially separate from a second bridge part of the first bridgecircuit, the spatially separate first and second bridge parts with aspacing therebetween forming the first bridge circuit, and wherein thefirst bridge circuit comprises resistors based on a first transferfunction that indicates a resistance of the resistors, and a secondmagnetic field sensor, wherein the second magnetic field sensor isarranged spatially entirely in the spacing between the first bridge partand the second bridge part of the first bridge circuit, wherein thesecond magnetic field sensor comprises a second bridge circuit, whereinthe second bridge circuit comprises a first resistor based on a secondtransfer function coupled in series with a second resistor based on athird transfer function different from the second transfer function, anda third resistor based on the third transfer function coupled in serieswith a fourth resistor based on the second transfer function, the seriesconnection of the first and second resistors being coupled in parallelto the series connection of the third and fourth resistors, and whereinthe first resistor, the second resistor, the third resistor, and thefourth resistor each exhibit at least one of a giant magnetoresistanceand a tunnel magnetoresistance.
 2. The device of claim 1, wherein theresistors of the first bridge circuit exhibit at least one of a giantmagnetoresistance and a tunnel magnetoresistance.
 3. The device of claim1, wherein the second bridge circuit comprises at least one resistorcomprising elliptical elements coupled in series.
 4. The magnetic fieldsensor device of claim 1, wherein the first resistor and the fourthresistor have larger sensitivity ranges than the second resistor and thethird resistor, and wherein the magnetic field sensor device furthercomprises a control circuit to derive a speed of modulation of amagnetic field from a measurement of the first magnetic field sensor andto derive a proximity of a magnet from a measurement of the secondmagnetic field sensor, the magnet being arranged on a moving object andadjacent to the magnetic field sensor device.
 5. The device of claim 1,wherein the first bridge circuit comprises a differential bridgecircuit.
 6. The magnetic field sensor device of claim 1, wherein thefirst and second bridge circuits are arranged in a same plane.
 7. Themagnetic field sensor device of claim 1, wherein the first bridgecircuit is configured to measure a first magnetic property, and whereinthe second bridge circuit is configured to measure a second magneticproperty different than the first magnetic property.
 8. A magnetic fieldsensor device, comprising: a first magnetic field sensor comprising afirst bridge circuit having a first bridge part comprising first andfourth resistor elements, and a second bridge part comprising second andthird resistor elements, wherein the first bridge part and the secondbridge part are spatially separate from one another with a spacingtherebetween, and wherein the first through fourth resistor elementscomprise a same design based on a same transfer function that indicatesa resistance of the first through fourth resistor elements; and a secondmagnetic field sensor comprising a second bridge circuit entirelydisposed in the spacing between the first bridge part and the secondbridge part of the first bridge circuit of the first magnetic fieldsensor, wherein the first and fourth resistor elements are disposed onone side of the second magnetic field sensor, and the second and thirdresistor elements are disposed on a second, opposing side of the atleast a portion of the second magnetic field sensor, wherein the secondbridge circuit comprises fifth through eighth resistors each exhibitingat least one of a giant magnetoresistance and a tunnelmagnetoresistance, and wherein the fifth resistor and the eighthresistor have larger sensitivity ranges than the sixth resistor and theseventh resistor.
 9. The magnetic field sensor device of claim 8,wherein the first bridge circuit is configured to measure a firstmagnetic property, and wherein the second bridge circuit is configuredto measure a second magnetic property different than the first magneticproperty.
 10. The magnetic field sensor device of claim 8, wherein thefifth resistor is based on a second transfer function and is coupled inseries with the sixth resistor, wherein the sixth resistor is based on athird transfer function different from the second transfer function,wherein the seventh resistor is based on the third transfer function andis coupled with the eighth resistor, wherein the eight resistor is basedon the second transfer function, and wherein the series connection ofthe fifth and sixth resistors being coupled in parallel to the seriesconnection of the seventh and eighth resistors.
 11. The magnetic fieldsensor device of claim 8, further comprising a control circuit to derivea speed of modulation of a magnetic field from a measurement of thefirst magnetic field sensor and to derive a proximity of a magnet from ameasurement of the second magnetic field sensor, the magnet beingarranged on a moving object and adjacent to the magnetic field sensordevice.